Method of destructively distilling wood.



UNITED STATES rAT INT OFFICE.

301mm: 0. PALMER, orrnnsncotn, FLOR-IDA, assrcnon, BY Mnsnn ASSIGNMENTS, rro THE GOVERNMENT on THE UNITED STAT-ES AND THE rnoze'nn on THE UNITED STATES.

1,259,277 Specification oi Letters Patent.

No Drawing.

METHOD OF DESTRUCTIVELY DISTILLING: 'WOOD.

Patented Mar, 12, 1918.

' App'licationfilciMarch 23, 1917. Serial No. 157,859.

(DEDICATED TO THE PUBLIC.)

method-of carbonizing Wood, such products.

as aceticacid and methylalcohol are formed and-m'ayberecovered from the condensed vapors by suitable methods of refining and it is also-known-that the yield of these productsris much less than-the chemical analysis of the wood indicates shoul'dbe recovered.

It is-also well lmown that if wood is heated in a-boiling-solutionof a mineralacid, such sulfuric acid or hydrochloric acid, at a temperature much lower than the destructive distillationof-wood, acetic acid will'be'formedbut no methyl alcohol is produced by this means. The use of these acids at the temperature of the-destructive distil lation'of wodd would not-.be practicable as the acids are ei-ther volatilized or oxidized and lost.

I-have discovered-that if wood is destructively distilled with an acid like phosphoric acid,'- which is. non-volatile, at the maximum temperatures used in the carbonization of wood, it is possible greatly to in crease the amountof acetic acid and methyl alcohol formed" from the wood as compared to the usual methods-"of distillation.

In the practice of my invention the wood in anydesiredsize or form is-placed in a solution 0t orthophosphoric acid, pyrophos phoric acid,- 01" metaphosphoric acid of any desired or convenient strength, depending on the amount of'acid it is desired to get intothe-wood, and the wood is then penetrated by the acid by any of the means used for the penetration of wood. by oils or other liquids, as employed in the. PlOfiBYWLJiOll of Wood against decay. The amount of acid to be forced into the wood will. vary with conditions, but may not exceed more than 21 per cent. oi the dry weight of the wood. The

wood is then removed from the solution and thecxccss Water may be evaporated, causing an increase in the strength of the acid. Fcilowing this operation, the wood is placed in any suitable retort and carbonized, either in the usual manner or by causing the vapors arising from the wood to be confined, so that a pressure exists in the retort, preferably not exceeding 300 pounds per square inch. The vapors issuing from the retort are condensed and refined, in the usual manner, for the re covery of the valuable products such as acetic acid and methyl alcohol. By this means the amount of acetic acid recovered,

maybe as much as it per cent. of the weight 01 the Wood, compared to a normal yield of.

4;; per cent, and the amount of methyl alcohol recovered as much as per cent. of

the Weight of the Wood compared to a nor inal yield of 2 percent.

having thus described my invention, I. claim:

1. The process of treating Wood with a solution of phosphoric acid by any means that will procure an intimate mixture oi Wood and acid and after evaporating any excess Water to'place the wood in a suitable retort or carbonizing apparatus and destruclively distill by applying heat to the retort in any manner that will attain a temperature sufficient to cause the formation of acetic acid and methyl alcohol.

'2. The process of treating WOOd with a se lution of orthophosphoric acid to get an in tinrate mixture of wood and acid and heat- .ing the Wood in a suitable retort to a temperature that will secure the ina-Ximum"for1nation'of acetic acid and methyl alcohol and confining the vaporo-us products arising from the wood. until they areuuder a pressure not exeeedin- 300 pounds per square inch, al-

lowing t e vapors to escape under pressure through a. suitable outlet to a condenser where they are.c0ndensed and subsequently 5 refined by any suiteble means for the recovery of acetic acid, methyl alcohol or other Valuable products.

in testimony whereof, I aifix my signature in the presence of two subscribing witnesses.

' ROBERT C. PALMER.

Witnesses:

' ALMA E. FISHER,

GoNxfmR F.- ELDREDGE. 

